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Subject[PATCH tip/core/rcu 17/40] srcu: Allow SRCU to access rcu_scheduler_active
Date
This is primarily a code-movement commit in preparation for allowing
SRCU to handle early-boot SRCU grace periods.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcutiny.h | 6 +++---
kernel/rcu/tiny_plugin.h | 9 +++++----
kernel/rcu/tree.c | 2 +-
kernel/rcu/tree_exp.h | 12 -----------
kernel/rcu/update.c | 52 +++++++++++++++++++++++++++++++-----------------
5 files changed, 43 insertions(+), 38 deletions(-)

diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 6c9d941e3962..5219be250f00 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -217,14 +217,14 @@ static inline void exit_rcu(void)
{
}

-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
extern int rcu_scheduler_active __read_mostly;
void rcu_scheduler_starting(void);
-#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+#else /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */
static inline void rcu_scheduler_starting(void)
{
}
-#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+#endif /* #else #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */

#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE)

diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
index df3a60e19f07..371034e77f87 100644
--- a/kernel/rcu/tiny_plugin.h
+++ b/kernel/rcu/tiny_plugin.h
@@ -52,7 +52,7 @@ static struct rcu_ctrlblk rcu_bh_ctrlblk = {
RCU_TRACE(.name = "rcu_bh")
};

-#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU)
#include <linux/kernel_stat.h>

int rcu_scheduler_active __read_mostly;
@@ -65,15 +65,16 @@ EXPORT_SYMBOL_GPL(rcu_scheduler_active);
* to RCU_SCHEDULER_RUNNING, skipping the RCU_SCHEDULER_INIT stage.
* The reason for this is that Tiny RCU does not need kthreads, so does
* not have to care about the fact that the scheduler is half-initialized
- * at a certain phase of the boot process.
+ * at a certain phase of the boot process. Unless SRCU is in the mix.
*/
void __init rcu_scheduler_starting(void)
{
WARN_ON(nr_context_switches() > 0);
- rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
+ rcu_scheduler_active = IS_ENABLED(CONFIG_SRCU)
+ ? RCU_SCHEDULER_INIT : RCU_SCHEDULER_RUNNING;
}

-#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+#endif /* #if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_SRCU) */

#ifdef CONFIG_RCU_TRACE

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 00390965c843..5e827d636e0b 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3981,7 +3981,7 @@ early_initcall(rcu_spawn_gp_kthread);
* task is booting the system, and such primitives are no-ops). After this
* function is called, any synchronous grace-period primitives are run as
* expedited, with the requesting task driving the grace period forward.
- * A later core_initcall() rcu_exp_runtime_mode() will switch to full
+ * A later core_initcall() rcu_set_runtime_mode() will switch to full
* runtime RCU functionality.
*/
void rcu_scheduler_starting(void)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index a1f52bbe9db6..51ca287828a2 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -737,15 +737,3 @@ void synchronize_rcu_expedited(void)
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);

#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
-
-/*
- * Switch to run-time mode once Tree RCU has fully initialized.
- */
-static int __init rcu_exp_runtime_mode(void)
-{
- rcu_test_sync_prims();
- rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
- rcu_test_sync_prims();
- return 0;
-}
-core_initcall(rcu_exp_runtime_mode);
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 55c8530316c7..c5df0d756900 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -124,7 +124,7 @@ EXPORT_SYMBOL(rcu_read_lock_sched_held);
* non-expedited counterparts? Intended for use within RCU. Note
* that if the user specifies both rcu_expedited and rcu_normal, then
* rcu_normal wins. (Except during the time period during boot from
- * when the first task is spawned until the rcu_exp_runtime_mode()
+ * when the first task is spawned until the rcu_set_runtime_mode()
* core_initcall() is invoked, at which point everything is expedited.)
*/
bool rcu_gp_is_normal(void)
@@ -190,6 +190,39 @@ void rcu_end_inkernel_boot(void)

#endif /* #ifndef CONFIG_TINY_RCU */

+/*
+ * Test each non-SRCU synchronous grace-period wait API. This is
+ * useful just after a change in mode for these primitives, and
+ * during early boot.
+ */
+void rcu_test_sync_prims(void)
+{
+ if (!IS_ENABLED(CONFIG_PROVE_RCU))
+ return;
+ synchronize_rcu();
+ synchronize_rcu_bh();
+ synchronize_sched();
+ synchronize_rcu_expedited();
+ synchronize_rcu_bh_expedited();
+ synchronize_sched_expedited();
+}
+
+#if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU)
+
+/*
+ * Switch to run-time mode once RCU has fully initialized.
+ */
+static int __init rcu_set_runtime_mode(void)
+{
+ rcu_test_sync_prims();
+ rcu_scheduler_active = RCU_SCHEDULER_RUNNING;
+ rcu_test_sync_prims();
+ return 0;
+}
+core_initcall(rcu_set_runtime_mode);
+
+#endif /* #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_SRCU) */
+
#ifdef CONFIG_PREEMPT_RCU

/*
@@ -817,23 +850,6 @@ static void rcu_spawn_tasks_kthread(void)

#endif /* #ifdef CONFIG_TASKS_RCU */

-/*
- * Test each non-SRCU synchronous grace-period wait API. This is
- * useful just after a change in mode for these primitives, and
- * during early boot.
- */
-void rcu_test_sync_prims(void)
-{
- if (!IS_ENABLED(CONFIG_PROVE_RCU))
- return;
- synchronize_rcu();
- synchronize_rcu_bh();
- synchronize_sched();
- synchronize_rcu_expedited();
- synchronize_rcu_bh_expedited();
- synchronize_sched_expedited();
-}
-
#ifdef CONFIG_PROVE_RCU

/*
--
2.5.2
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